Electronic tube



March 20, w w E|TE| ET AL ELECTRONIC TUBE Filed June 30,- 1942 2Sheets-Sheet l INVENTORS WILL/AM M E/TEL (/AC M- CULLOUGH fie 5 f THEIRATTORNEY Patented Mar. 20, 1945 UNITED STATES PATENT OFFICE ELECTRONICTUBE Application June 30, 1942, Serial No. 449,146

4 Claims.

Our invention relates to an electronic tube particularly adapted forhigh frequency Work.

It is among the objects of our invention to provide a tube of smallphysical size, having an improved structure of, arrangement for andmounting of the electrodes and leads in the envelope.'

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of our invention. It is to be understood that we do notlimit ourselves to this disclosure of species of our invention, as wemay adopt variant embodiments thereof within the scope of the.

claims.

Referring to the drawings:

Figure 1 is a side elevational view of a tube embodying the improvementsof our invention; and

Figure 2 is a plan view of the same.

Figure 3 is a vertical sectional view on the same scale, taken in aplane indicated by line 3--3 of Figure 2.

In terms of broad inclusion, our tube comprises an envelope enclosing aplurality of coaxial electrodes including a cathode and grid and plate.The plate is supported on a lead disposed coaxially of the electrodes;and the grid is supported on a pair of leads disposed transversely ofthe electrode axis. The envelope comprises a pair of cup-shaped sectionssealed together along abutting edges. Cathode leads are sealed to thebase section, while the plate and grid leads are sealed to the bodysection of the envelope.

In greater detail, and referring to the drawings, our tube comprises a,cylindrical envelope of glass or the like having a body section 2 and abase section 3, both cup-shaped and fused together along abutting edgesat seal 4 in a plane lying transversely of the envelope. The basesection is shorter than the body; more like a shallow dish compared tothe deeper cupped body 2. A tabulation for evacuating the envelope isconnected to the body section and, after exhaust, is sealed off the pumpat point 5. The envelope is of small physical size, say about 1 inchesin diameter by about 2 inches in length.

Within the envelope are mounted a plurality of coaxial electrodes,including a plate 6, grid 1 and cathode 8. The plate or anode 6comprises a pair of drum-like sections, preferably'of tantalum, disposedend-to-end. Integral flanges 9 at adjacent ends of the sections arewelded together to form a unitary plate structure. The flanges also forman annular heat radiating fin about the mid-portion of the plate. Ahemispherical cap I l of tantalum is secured over the top of the tubularplate by means of depending tabs I2 welded to the upper plate section.Arched recesses l3 between the tabs form vent openings.

Plate lead I4 is disposed coaxially of the electrodes and projects thruthe top of envelope section 2 at seal IS. The lead is preferably a heavyrod of tungsten. Support for the plate is provided by a yoke-shapedstrap l l of tantalum having arms spot Welded to cap I 1. Both partsbeing of tantalum they weld readily. It is more diflicult to weld totungsten however, and we preferably first spot weld a piece of nickel IEto the bracket and then weld this to the end of lead M. The body ofnickel interposed between the parts alloys or fluxes with both thetantalum and tungsten providing a strong joint. The weld is also clean,devoid of oxides and contamination which, if present, would make itdifficult to outgas the parts during evacuation.

Supporting bracket I! also functions to thermally insulate lead M fromplate 6, due to the fact that tantalum is a poor conductor of heat andbecause the wide arms of the yoke-shaped strap radiate heat efficiently.Cap ll presents considerable heat radiation surface and aids inthermally isolating the lead from the plate. As a result, the glass atthe lead seal is kept cool and cracking of the seal is prevented.

Grid 1 is of the cage type, preferably of platinum, terminating in atantalum base ring IS. The grid is supported on a pair of alignedtungsten leads 2| extending transversely of the electrode axis andprojecting thru the sides of envelope section 2 at seals 22. Support forthe grid is provided by an oblong loop-like bracket 23 formed by a stripof tantalum bent and welded to make a continuous band. Terminal ring I!)of the grid is welded between the legs of the loop intermediate the endsof the bracket; and the bracket ends are in turn welded to the opposedinner ends of leads 2 l. Pieces 24 of nickel are interposed between theleads and bracket to flux the welds. This grid bracket provides a rigidsupport for the grid, and also has good heat radiating properties neededfor keeping seals 22 cool.

Cathode 8 is supported on three leads including a pair of short leads 26and a longer central lead 2?. The center lead is disposed coaxially withthe electrodes and has a reduced upper portion projecting thru thecathode. These leads, also preferably of tungsten, extend thru thebottom of base section 3 at seals 28.

The cathode comprises a pair of filament coils of thoriated tungstenhaving interspaced convolutions concentrically arranged about the axisof the electrodes. The upper ends of the coils are connected to centerlead 21, preferably by Wrapping the ends of the filament Wires about thelead and Welding. The lower ends of the coils are Welded to tantalumstraps 29 which in turn are Welded to leads 26.

Our tube is fabricated by forming the envelope in two separate sectionsWhich, prior to sealing together, are open at one end. Plate lead it andgrid leads 2! are sealed in place in body section 2. The plate assemblyis Welded to lead 14, after Which the grid assembly is Welded to leads2!. An alternate procedure is to first Weld the electrodes to the leads,apart from the envelope, and then seal the leads to the glass, using asuitable jig to maintain proper spacing and alignment.

The cathode leads are sealed to the separate base section, and filament8 is welded in place. Since the cathode leads project out thru the openmouth of the shallow base section, the filament coils may be readilypositioned and welded.

iter mounting the electrodes the filament is centered within the gridand the two envelope sections are fused together along abutting edges atseal 4.

We claim:

LAn electronic tube comprising an envelope embodying a pair ofcup-shaped sections sealed together along abutting edges, a plurality ofcoaxial electrodes including a cathode and grid and plate in theenvelope, a lead coaxial with the electrodes and sealed to one of saidsections, a pair of leads disposed transversely of the electrode axisand sealed to the side of the last men tioned section, means supportingthe plate on the coaxial lead, means supporting the grid on said pair ofleads, and leads for the cathode sealed to the other section of theenvelope.

2. An electronic tube comprising an envelope embodying a pair ofcup-shaped sections sealed together along abutting edges, a plurality ofcoaxial electrodes including a cathode and grid and plate in theenvelope, a lead coaxial with the electrodes and sealed to one of saidsections, a pair of aligned leads disposed transversely of the electrodeaxis and sealed to the side of the last mentioned section, 'meanssupporting the plate on the coaxial lead, means supporting the grid onsaid pair of leads, and leads for the cathode sealed to the othersection of the envelope.

3. An electronic tube comprising an envelope embodying a pair ofcup-shaped sections sealed together along abutting edges, a plurality ofcoaxial electrodes including a cathode and grid and plate in theenvelope, a lead coaxial with the electrodes and sealed to one of saidsections, a pair of leads disposed transversely of the electrode axisand sealed to the side of the last mentioned section, a cap on one endof the plate, a bracket on the cap for supporting the plate on thecoaxial lead, means adjacent the other end of the plate for supportingthe grid on said pair of leads, and leads for the cathode sealed to theother section of the envelope.

4. An electronic tube comprising an envelope, a grid in the envelope, apair of aligned leads disposed transversely of the grid axis and sealedto the envelope, and a grid support comprising an oblong loop securedintermediate its ends to the grid and at its ends to said leads.

NILLIAM WV. EITEL. JACK A. MCCULLOUGH.

